Migrate codebase to TypeScript

[Github](https://github.com/actions) has [re]-written [many](https://github.com/actions/setup-go) [of](https://github.com/actions/setup-node) [their](https://github.com/actions/toolkit) [actions](https://github.com/actions/starter-workflows) in TypeScript and also provides a [Github action TypeScript template](https://github.com/actions/typescript-action). [We should also be using TypeScript](https://www.typescriptlang.org/why-create-typescript).

Also, there was some work done for a [VS Code grype extension](https://github.com/anchore/grype-vscode) that was using Typescript, so we should look to refactor this to a common library for use between tools.

Start by reviewing the existing JavaScript codebase, the linked GitHub TypeScript action template, and the related grype-vscode work. Determine the migration scope and shared-library boundaries before proceeding; done would mean the codebase uses TypeScript and the relevant tools can share the refactored library.

Written by the indexing model from the issue text.